This invention relates to a therapy for clearing the blood of unwanted carbon monoxide and anaesthetic chemicals and for rapidly re-oxygenating that has had it""s oxygen level depleted by environmental conditions i.e. carbon monoxide poisoning or smoke inhalation. The invention includes the means of delivering the therapy in a convenient manner whether given in-situ, in an ambulance or other emergency response vehicle, or at the hospital or other care facility, and whether administered by medical professionals or paramedical personnel. The device relates in general to pneumatic/mechanical control of respirator gas supply control devices and in particular to gas selection, automatic shut off of the carbon dioxide, purging, metering and mixing of the therapeutic gases.
Carbon monoxide (CO) is a tasteless, colorless, odourless gas. Thus it is undetectable by potential victims. The blood prefers CO to oxygen by a ratio of 200:1. As a result, relatively small amounts of CO in the air can cause CO poisoning. CO attaches to blood forming carboxyhemoglobin, thus starving the brain and other organs and tissues for oxygen (O2). Carbon monoxide poisoning occurs when carboxyhemoglobin levels are high enough to impair cellular functions. Symptoms of carbon monoxide poisoning include drowsiness, nausea and possibly death. The CO poisoning rate is significant, with over 70,000 hospital visits and 10,000 deaths per year in the U.S.
The cellular oxygen starvation from CO poisoning can cause death, or long-term, non-reversible health problems (i.e. to the brain, heart or neurological system). If a CO poisoning victim does not die, the average body will clear carboxyhemoglobin at the following typical rates:
Spontaneous breathingxe2x88x92cleansing half-life =220 minutes; Breathing pure O2=40 minutes; Hyperbaric chamber=20 minutes.
While the best current therapy is placing the patient in a hyperbaric chamber, these chambers are usually unavailable (only about 700 exist world-wide) and are rarely used. Typically these chambers require a xe2x80x9cwarm-upxe2x80x9d time of 2 hours, which largely negates their theoretical usefulness. That is, significant permanent damage may have already occurred before the treatment can be commenced.
The current therapy of choice is to administer pure O2. As suggested above, pure O2 would require approximately 2 hours to clear 87.5% of the CO from the bloodstream (e.g. 40 minutes=50% of CO is eliminated; 80 minutes=25%; 120 minutes=12.5%). Breathing pure O2 has an unfortunate side effect; it lowers the respiratory rate and reduces the exchange of gases in the lungs, thereby prolonging the tissue starvation period. Accordingly, there is a need for a device that would overcome these disadvantages.
Typical respirator gas supply control devices, particularly those used for mixing gases under pressure and feed a delivery line of a respirator, or medical device, are too large and bulky to be used in situ or in emergency vehicles. They also require the operation of a skilled, medical practitioner to properly administer. A complete system that can be used by emergency and paramedical should have a gas selection device, an automatic shut off of the carbon monoxide a purging system, metering of the gases and a mixing chamber to promote a homogeneous mixture of gases and sized for in-situ or vehicle as well as hospital emergency room use. It should be able to use a whole range of different gas storage systems for input and demand regulators and facemasks as output. It can not rely on electrical control of the gas flow and mixing as power demand for both in situ or emergency vehicle applications is already greater than is reasonable to expect. Also electrical power at fire and other emergency sites is problematical to provide and higher priority uses get first use of this power. Finally battery power is not acceptable as the system must operate every time demanded regardless of the interval between demand and maintenance of batteries is a low priority item for emergency care providers.
For example, U.S. Pat. 3,441,041 allows for either atmospheric or compressed air to be used for a breathing apparatus but the mixture device is not easily portable, and requires adjustment by a trained individual when dealing with a patient to determine if the by-pass should be opened or closed and to adjust the compressed air flow based on respiration demands and the state of the patient""s health.
U.S. Pat. 4,535,797 discloses a device that uses flow to keep the by-pass open and the by-pass is required to open the gas flow valve for the first time. Should the CO2 supply fail, the O2 supply will shut and the patient""s therapy is terminated.
U.S. Pat. 4,549,563 maintains a constant ratio between two gases, G1 and G2, by keeping the pressure of both gases P1 and P2 constant and keeps P1 constant at a set rate of flow through the use of a pressure limiter.
The device disclosed in U.S. Pat. 4,549,563 does not provide for automatic shut off of the CO2 gas stream should the O2 stream become clogged. This shortcoming would expose the patient to an asphixyant and would not revert to the previously accepted therapy. In U.S. Pat. 4,549,563 the practitioner operates the flush system described in case the patient requires pure O2 instead of the gas mixer. Such facemasks are commercially available and are not shown in the drawings. Also the system in 4,549,563 has no means of purging, which would mean that the second patient would face an incorrect mixture or if the system selection was changed, for example from O2 to CO2 then the patient would have to inhale the incorrect mixture prior to receiving the correct therapeutic gases.
U.S. Pat. 4,313,436 mixes O2 and other medical gases for patients. It requires electronic sensing to determine if the gas mixture is correct and if not then causes a pressure pulse to close the by-pass thereby allowing only pure O2 to enter the facemask. The use of electronics that have a large demand for power, i.e. 4 sensors and an automatic controller, are not feasible for in-situ on in vehicle use where power demand is already quite high and the most frequent operational problem is dead batteries due to limited maintenance time. Also this device has up to 5 separate valves that need to be adjusted by the medical practitioner to ensure the patient is receiving the proper gas mixture depending on his state. This degree of adjustment is inimical to the use by paramedical and emergency personnel. The system in 4,313,436 lacks a means of purging and only has two selection options, no mixture or mixture. Since there is no intermediary stage the operator is not prompted to purge the system.
U.S. Pat. 4,827,965 uses a venturi nozzle to simultaneously meter and mix the two gases in proper proportions. This scheme means that pressure of the two gases varies over the flow demand regime and that the charge may be stratified. Finally the system in 4,827,965 does not have a means to shut off the CO2 mixture thus potentially exposing the patient to an asphixyant. Nor does it allow selection of different options (i.e. O2 only, off, mix or off). Nor does it offer a means of purging the system except by drawing off the first amount of improper mixture.
Under U.S. Pat. 5,727,545, one embodiment requires electronic sensing of two temperatures and a pressure to control the action of four flow regulators. In a second embodiment, it requires electronic sensing of two temperatures and a pressure to control the action of two flow regulators. The by-pass is driven electronically so that any failure of the electrical system would endanger the patient""s life. Metering and mixing are all electronic and it has no purging means. The use of electronics that have a large demand for power are not feasible for in-situ on in vehicle use where power demand is already quite high and the most frequent operational problem is dead batteries due to limited maintenance time.
U.S. Pat. 4,508,143 discloses the use of a cam actuator to open a valve. It opens two poppet valves either automatically or manually. 4,508,143 has no other features that could deliver or control the therapeutic gas delivery.
The invention provides a therapy clearing the blood of unwanted carbon monoxide and anaesthetic chemicals and for rapidly re-oxygenating that has had its oxygen level depleted by environmental conditions, i.e. carbon monoxide poisoning or smoke inhalation. The invention includes delivering the therapy in a convenient manner in situ, in an ambulance or other emergency response vehicle, or at the hospital or other care facility. It may be administered by medical professionals or paramedical personnel. The device relates in general to respirator gas supply control devices and in particular to gas selection, automatic shut off of the carbon monoxide, purging, metering and mixing of the therapeutic gases.
It is a great improvement on the current therapy, using pure O2, in that it is more rapidly clears carboxyhemoglobin from the patient""s blood stream. Also it does not lower the respiratory rate or reduce the exchange of gases in the lungs, thereby prolonging the tissue starvation period. In fact the body""s autonomous responses in the presence of a CO2 rich environment is to increase the rate of respiration (panting) thus further decreasing the tissue starvation period. While the method of invention and the use of a hyperbaric chamber are both effective, a hyperbaric chamber is impractical for in situ and vehicle applications due to their size, cost, long warm up time and requirement for trained medical practitioner for operation.
Cellular oxygen starvation from CO poisoning, or smoke inhalation, can cause death, or long-term, non-reversible health problems (i.e. to the brain, heart or neurological system). In the United States alone there are 70,000 hospital visits and 10,000 deaths per year due to CO poisoning. Thus a new therapy that radically improves the outcomes of patients exposed to CO poisoning is needed.
The invention also includes a device for delivering the improved therapy for in situ, in vehicles (i.e. ambulance or fire truck) and institutional (i.e. hospital) locations. It avoids the above-described shortcomings for example where the system requires electric power to properly operate, making it impractical for most emergency applications. It avoids the requirement for a trained medical practitioner to properly operate and adjust the system while monitoring the patient""s state of health. It avoids the requirement to add other required functions to the system with external components.
The invention optionally includes all the functions required of an integrated system: selection of therapy; automatic shut-off of CO2; (i.e. automatic use of current therapy pure O2) or in case of O2 interruption automatic use of atmospheric air; precision metering of both gases; excellent mixing of both gases; and system purging. One embodiment allows for the use of the use of any O2 and C O2 supply to accommodate institutional demands (i.e. hospitals). The first embodiment includes a pneumatic control device. The second embodiment includes its own portable CO2 supply to allow use with existing portable O2 supplies found in all emergency response vehicles. The second embodiment contains all items required for the therapy except the external O2 supply.
A cam actuator is used to select the choice of gas that the patient receives and is a four-position, rotary, manual switch. It can either be O2, off, O2/CO2, off. The two intermediary xe2x80x9coffxe2x80x9d positions allow for the patient to breathe atmospheric air and are a reminder to the operator to purge the system prior to moving to the next selection position.
Should one of the source gas pressures become too low to maintain a proper therapeutic gas mixture then the CO2 flow would be halted by the shut-off valve. A CO2 shutoff is operated by differential pressure between the O2 and the CO2 gas mixture; failing a proper supply of O2, the CO2 shut-off closes so that only atmospheric air or O2 can be inhaled. This is acceptable as the system reverts to the previously acceptable therapy. In case of O2 flow interruption the CO2 flow stops and automatically the patient inhales atmospheric air through the facemask by-pass valve.
The pressure of one gas G 1 (O2) maintains the flow of the other gas G2 (CO2), since PI keeps the G2 flow passage open. Metering is done separately for each gas and is automatic and based on sonic flow of the gases, but accepts sub-sonic flow for either or both gases. Metering keeps the flow proportional regardless of outlet demand, and mixing is done in a separate chamber where the gas path maximises the chance of a homogeneous mixture.
The invention relates to an apparatus and method for clearing the blood of unwanted carbon monoxide and/or anaesthetic chemicals and for rapidly re-oxygenating that has had it""s oxygen level depleted, for example by environmental conditions i.e. carbon monoxide poisoning or smoke inhalation. The therapy includes respiration by the patient of a mixture of CO2 and O2. The apparatus for treating preferably involves administering to the subject oxygen from a source of oxygen and carbon dioxide from a source of carbon dioxide, comprises:
an oxygen conduit defining an oxygen inlet and an oxygen outlet, the oxygen inlet adapted for fluid communication with the source of oxygen;
a carbon dioxide conduit defining a carbon dioxide inlet and a carbon dioxide outlet, the carbon dioxide inlet adapted for fluid communication with the source of carbon dioxide;
a means for combining the oxygen and the carbon dioxide, the means downstream from the oxygen outlet and the carbon dioxide outlet; and
a means for administering the combined oxygen and carbon dioxide to the subject.
The invention also includes a portable kit including the apparatus. The invention also includes a method for removing carbon monoxide and/or anaesthetic chemicals from blood and for rapidly re-oxygenating that has had it""s oxygen level depleted, including administering to a subject an effective amount of combined oxygen and carbon dioxide from the apparatus. The invention also includes the use of the apparatus for removing carbon monoxide and/or anaesthetic chemicals from blood and for rapidly re-oxygenating that has had it""s oxygen level depleted.
Oxygen and carbon dioxide therapy using the apparatus and methods of the invention can produce a clearing half-life of about 20 minutes.
The invention relates to an improved therapy for clearing the blood of unwanted carbon monoxide and anaesthetic chemicals and for rapidly re-oxygenating that has had it""s oxygen level depleted by environmental conditions i.e. carbon monoxide poisoning or smoke inhalation. The therapy includes respiration by the patient of a mixture of CO2 and O2 . The invention includes an apparatus and method for delivering the improved therapy in a convenient manner whether given in-situ, in an ambulance or other emergency response vehicle, or at the hospital or other care facility, and whether administered by medical professionals or paramedical personnel, and does not require the use of electrical power. In one embodiment, the apparatus acts as a pneumatic control device for the therapeutic gas mixture and where O2 and CO2 are stored. Preferably, pressure is regulated externally, an external buffer volume is stored externally and/or the demand regulator and facemask are connected to the equipment.
The invention also includes a method and apparatus for delivering the improved therapy, in the second embodiment, where all necessary functions are delivery of the therapeutic gas mixture is self-contained, with the sole exception of the O2 supply.
The invention also includes a control system, in the first embodiment, which preferably includes: supplied gas shut-off valves; therapy selector switch; automatic shut-off valve for CO2 supply to avoid asphyxiating the patient; separate CO2 and O2 metering valves; a common gas mixing chamber, outlet ports to the buffer volume; outlet ports to the demand regulator/facemask; a means to purge the system and the buffer volume of previous gas mixtures prior to each new use. This system requires external connections to pressurised CO2 and O2, a buffer volume and the demand regulator/facemask to operate.
The invention also includes a portable apparatus and method of delivering the improved therapy, for emergency personnel and first aid care givers at the emergency site, in the second embodiment, which includes: pressure regulation of supplied O2 ; CO2 cylinder; pressure regulation of supplied CO2; CO2 and O2 gas shut-off valves; therapy selector switch; automatic shut-off valve for CO2 supply to avoid asphyxiating the patient; separate CO2 and O2 metering valves; a common gas mixing chamber; a buffer volume; a demand regulator, hose and facemask; a means to purge the system and the buffer volume of previous gas mixtures prior to each new use. This embodiment only requires connection to an outside, readily available source of pressurised O2 to operate. The invention also includes alternate methods of providing a suitable gas metering orifice. The invention also includes a member to filter either or both of the therapeutic gases prior to metering.
The invention also relates to a gas metering and mixing apparatus for gases under pressure, particularly for respirators and medical devices, comprising a plurality of gas meters, a gas mixer device, a plurality of compressed gas supply lines connected to said gas meters, a plurality of mixed gas delivery lines extending out of said gas mixer device for the discharge of a mixture of gases from said compressed gas supply lines from said gas meters and from said gas mixer device to a demand regulator, hose and facemask and to a buffer storage volume, and a means of selecting which gases, O2, mixture or none, are sourced to said metering and mixing device and at least an automatic shutoff valve for one of the therapeutic gases, CO2, which could in excess cause patient asphyxiation without said shut-off valve performing its function and with a means of purging the system including the buffer volume of mixed gases (or O2 as appropriate). The automatic shut-off valve preferably includes means of adjusting said valve to vary the pressure in which it opens. The invention also includes a gas metering and mixing apparatus, wherein said metering can be adjusted to vary the proportions of the two different therapeutic gases. The apparatus preferably includes the use of sonic nozzles to meter said therapeutic gases. The invention also includes alternate devices for metering said therapeutic gases. The gas metering and mixing apparatus includes the ability to add filtration to the system as a means of protecting the sonic nozzles. The invention also includes a gas metering and mixing apparatus which includes the ability to add filtration to the system to protect the alternate metering means.
The invention includes an apparatus for treating carbon monoxide poisoning in a subject by administering to the subject oxygen from a source of oxygen and carbon dioxide from a source of carbon dioxide, comprising:
an oxygen conduit defining an oxygen inlet and an oxygen outlet, the oxygen inlet adapted for fluid communication with the source of oxygen;
a carbon dioxide conduit defining a carbon dioxide inlet and a carbon dioxide outlet, the carbon dioxide inlet adapted for fluid communication with the source of carbon dioxide;
a means for combining the oxygen and the carbon dioxide, the means downstream from the oxygen outlet and the carbon dioxide outlet; and
a means for administering the combined oxygen and carbon dioxide to the subject.
In a variation, apparatus comprises a gas control means associated with the apparatus for controlling the pressure, flow rate and the ratio of the combined oxygen and carbon dioxide. The gas control means optionally comprises an oxygen regulator for controlling oxygen pressure and a carbon dioxide regulator for controlling carbon dioxide pressure, the oxygen regulator located between the oxygen source and the combining means and the carbon dioxide regulator located between the carbon dioxide source and the combining means. The regulators also control nominal flow rate of the oxygen and carbon dioxide.
In a variation, the control means further comprises an oxygen sonic nozzle downstream of the oxygen regulator and a carbon dioxide sonic nozzle downstream of the carbon dioxide regulator, the nozzles dispensing the oxygen and the carbon dioxide. The nozzles dispense the oxygen and the carbon dioxide according to a predetermined flow rate. The apparatus preferably also comprises a means for reducing the flow of carbon dioxide when the percentage of carbon dioxide in the combined carbon dioxide and oxygen exceeds about 6.5% by volume. In another embodiment, the reducing means prevents the flow of carbon dioxide.
The invention also includes a variation where the means for reducing the flow of carbon dioxide comprises a differential pressure sensor downstream of the carbon dioxide source and/or the oxygen source.
Another variation involves the reducing means being located proximate to the conduits and in fluid communication with the oxygen and the carbon dioxide sources.
In another variation, the reducing means of the apparatus comprises: a shutoff member located proximate to the carbon dioxide conduit having an on position in which the shutoff member permits the carbon dioxide to communicate from the carbon dioxide source to the combining means and an off position in which the shutoff member prevents the carbon dioxide from communicating from the carbon dioxide source to the combining means; an actuating means for actuating the shutoff member from the on position to the off position when the percentage of carbon dioxide in the combined carbon dioxide and oxygen exceeds about 6.5% by volume, the actuating means operably connected to the shutoff member and responsive to differential pressure in the oxygen conduit and the carbon dioxide conduit. Optionally, the actuating means comprises:
a piston means in fluid communication with the oxygen conduit, the piston means located proximate to the oxygen conduit and including a first position in which the piston means is biased away from the oxygen conduit and actuates the shutoff member to the on position and a second position in which it is biased towards the oxygen conduit and actuates the shutoff member to the off position;
a biasing means for urging the piston toward the second position;
the piston means normally biased by oxygen toward the first position against the force of the biasing means, the piston means being urged toward the second position by the biasing means when oxygen pressure decreases in the oxygen conduit.
According to another aspect of the invention, the combining means comprises a mixing chamber.
In another variation, the administering means of the apparatus comprises a face-mask including a conduit in fluid communication with the combining means, the face-mask adapted for placement over the face of the subject. The face-mask optionally comprises a pressure regulator.
The invention also includes the variation where the apparatus further comprises a buffer in fluid communication with the combining means, the buffer including combined oxygen and carbon dioxide.
In another variation, the administering means is capable of administering the combined oxygen and carbon dioxide to the subject in an amount effective to increase the breathing rate of the subject. The carbon dioxide is about 3.5 to 6.5 percent by volume of the combined oxygen and carbon dioxide.
According to another aspect of the invention, the combined carbon dioxide and oxygen are in a ratio of about 19:1 by volume.
In a variation, the combined carbon dioxide and oxygen have a pressure of about 1 atm to 20 psig.
The invention also includes the variation where the oxygen conduit and the carbon dioxide conduits are connected to a tubular housing and extend into the housing.
In another variation, the conduits of the apparatus are defined by the housing, and are integrally defined by the housing.
In a variation the apparatus is portable. Portable means that the apparatus can fit inside an emergency vehicle and is practical for use in an emergency situation (for example, it can preferably be carried by a person). It further comprises optionally a carbon dioxide tank capable of connection to the carbon dioxide conduit. The apparatus is preferably capable of fitting in a briefcase. The subject is a mammal, preferably a human. The apparatus is preferably operable without electric power. It is optionally pneumatically powered.
The invention may also include a selector means or device to control the flow of carbon dioxide and oxygen. In one embodiment, the selector means may include a rotary selector 40. The invention may also include a purging means or device, such as the valve 140 and port 160 for purging carbon dioxide and oxygen.
Another embodiment of the invention relates to a portable kit for treating carbon monoxide poisoning, comprising the apparatus of the invention.
This invention also includes a method of treating carbon monoxide poisoning, comprising administering to a subject an effective amount of combined oxygen and carbon dioxide from the apparatus disclosed. The invention also includes the use of an apparatus of the invention for treatment of carbon monoxide poisoning.
The invention includes an apparatus for treating carbon monoxide poisoning in a subject by administering to the subject oxygen from a source of oxygen and carbon dioxide from a source of carbon dioxide, comprising:
an oxygen conduit defining an oxygen inlet and an oxygen outlet, the oxygen inlet adapted for fluid communication with the source of oxygen;
a carbon dioxide conduit defining a carbon dioxide inlet and a carbon dioxide outlet, the carbon dioxide inlet adapted for fluid communication with the source of carbon dioxide;
a device for combining the oxygen and the carbon dioxide, the device downstream from the oxygen outlet and the carbon dioxide outlet; and
a device for administering the combined oxygen and carbon dioxide to the subject.
The apparatus optionally further comprises a gas control device associated with the apparatus for controlling the pressure, flow rate and the ratio of the combined oxygen and carbon dioxide.
The control device optionally further comprises an oxygen sonic nozzle downstream of the oxygen regulator and a carbon dioxide sonic nozzle downstream of the carbon dioxide regulator, the nozzles dispensing the oxygen and the carbon dioxide. The apparatus optionally further comprises a device for reducing the flow of carbon dioxide when the percentage of carbon dioxide in the combined carbon dioxide and oxygen exceeds about 6.5% by volume. The reducing device may comprise:
a shutoff member located proximate to the carbon dioxide conduit having an on position in which the shutoff member permits the carbon dioxide to communicate from the carbon dioxide source to the combining device and an off position in which the shutoff member prevents the carbon dioxide from communicating from the carbon dioxide source to the combining device;
an actuating device for actuating the shutoff member from the on position to the off position when the percentage of carbon dioxide in the combined carbon dioxide and oxygen exceeds about 6.5% by volume, the actuating device operably connected to the shutoff member and responsive to differential pressure in the oxygen conduit and the carbon dioxide conduit. The actuating device optionally comprises:
a piston device in fluid communication with the oxygen conduit, the piston device located proximate to the oxygen conduit and including a first position in which the piston device is biased away from the oxygen conduit and actuates the shutoff member to the on position and a second position in which it is biased towards the oxygen conduit and actuates the shutoff member to the off position;
a biasing device for urging the piston toward the second position;
the piston device normally biased by oxygen toward the first position against the force of the biasing device, the piston device being urged toward the second position by the biasing device when oxygen pressure decreases in the oxygen conduit. The device described 20 above may include various means, as described below.